package com.ding.pc;

import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * @author ding
 * @date 2021/7/17 18:33
 * 线程之间的通信问题： 生产者和消费者问题！ 等待唤醒，通知唤醒
 * 线程交替执行 A B 操作同一个变量 num=0
 *
 * A num+1
 * B num-1
 */


public class B {
    public static void main(String[] args) {
        Data2 data = new Data2();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "A").start();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "B").start();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.decrement();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "C").start();
        new Thread(() -> {
            for (int i = 0; i < 10; i++) {
                try {
                    data.increment();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }, "D").start();
    }

}

class Data2 {
    private int number = 0;
    final Lock lock = new ReentrantLock();
    final Condition notFull = lock.newCondition();
    final Condition notEmpty = lock.newCondition();


    //+1
    public void increment() throws InterruptedException {
        lock.lock();
        try {
            while (number != 0) {
                //等待
                notFull.await();
            }
            number++;
            System.out.println(Thread.currentThread().getName() + "=》" + number);
//        通知其他线程，我+1完毕了
            notEmpty.signal();
        } finally {
            lock.unlock();
        }
    }

    public void decrement() throws InterruptedException {
        lock.lock();
        try {


            while (number == 0) {
//            等待
                notEmpty.await();
            }
            number--;
//        通知其他线程，我-1完毕了
            System.out.println(Thread.currentThread().getName() + "=》" + number);
            notFull.signal();
        } finally {
            lock.unlock();
        }
    }
}

